Recently, attention has been directed to the use of combination of aqueous resin and water insoluble resinous particles as resinous vehicle in an aqueous coating composition, because of the specific rheological properties thereof. Usually, with said combination, it is possible to increase the resinous content of the composition without undesirably increasing the viscosity. Moreover, such compositions have been developed principally as a base coat or inter coat and are not possessed of the desired properties for a top coat like gloss and surface smoothness.
Under the circumstances, has long been desired an aqueous coating composition which maintains the desired properties of aqueous resin as excellent pigment dispersibility and the like, has excellent application characteristics and storage stability and furthermore the desired film performance for a top-coat as gloss and surface smoothness.
In a series of studies for the improvement of application characteristics of an aqueous coating composition comprising water insoluble resinous particles and aqueous resin, the inventors have concentrated efforts in finding out the correlation between the film properties and combination of resins, natures of resinous particles, compounding ratio of said aqueous resin and water insoluble resinous particles, solid content of the composition and the like, and found that particularly excellent composition in regard to pigment dispersion stability, application characteristic, storage stability, as well as the desired properties as top coat, i.e. gloss and surface smoothness of the coating, can be obtained by the combination of particular aqueous resin and particular water insoluble resionous particles. On the basis of said finding, the present invention has been made.